Directory:
    ${PENCIL_HOME}/samples/interstellar
SVN Id:
    $Id$
Maintainer:
    Fred A. Gent <fred.gent.ncl/gmail[dot]com>
Added:
    21-Jun-2016
Status:
    has been working in this form since 21-Jun-2016
    revised 27-Sep-2016
    revised 21-Mar-2018: upwind used to replace cs-dep diffusivities
                         constant low diffusivities can be included, which no
                         longer affect code stability. Stability is now 
                         controlled by shock mass diffusion and shock viscosity
    revised 09-Feb-2023: moved check_SN to before_boundary and only in first
                         time substep, skipped check_SN during pencil checks
    revised 06-Sep-2023: netheat not communicated and timestep uses RKF 
    revised 05-Mar-2025: timestep latest RKF low storage 4th order 
Recommended resolution:
    at least 160x160x1024 (maintain grid resolution <= 0.004 for larger Lx,Ly)
    sample is too confined to the midplane for auto-test rapid calculation 
Comments:
    Use the 1D model (an example is given in sample
    ../supernova-driven-turbulence/1D_ism_init) to obtain the file init_ism.dat
    containing density and temperatue profiles for the initial condition in
    this 3D supernova driven turbulence model of the ISM.  The 1D model has
    identical vertical grid and hydrodynamic run parameters.  Magnetic field
    and cosmic rays can be added to this 3D model
    
    The averaged SN heating substitutes for the SN driven turbulence and will be
    smoothly superceded by the SN explosions as the turbulence evolves.
    
    SN are spatially distributed according to a uniform distribution in the 
    horizontal plane and gaussian distribution vertically centred about the 
    centre of mass, which fluctuates near to the midlplane. Default SN frequency
    rates are milky way estimates and default mass and gravitional acceleration
    are taken from the solar vicinity.
    
    To obtain the 1D data file run
    > python ism_save.dat
    from the command line then copy the init_ism.dat file into the new 3D run
    directory
References:
    1. Gent, F.A., Shukurov, A., Fletcher, A., Sarson, G.R.S., &
       Mantere, M.J.: ``Supernova Driven Turbulence. I. The Multiphase
       Structure'',
       MNRAS, 432, 1396-1423